F05 indicates the boiler supply temperature
is excessive. When accompanied by the
red FAULT light and LOCKOUT flashing on
the display, this code indicates the supply
sensor temperature has exceeded 230oF and
a serious safety issue exists. The boiler will
not restart until a technician determines and
repairs the cause of excessive temperature
and pushes RESET on the display.
If the FAULT light is not illuminated and
this message is displayed, the supply
temperature of the boiler is at or above
210oF. The message will clear automatically
when the temperature drops below 194oF.
During the time that this fault is displayed,
the pump will be on.
- Check circulator pump operation.
- Ensure adequate flow through the boiler by accessing the status menu and determining there is less than a 50°F rise from the return thermistor to the supply thermistor.
- Check the direction of flow off the boiler circulator.
- Troubleshoot the dual supply thermistor by following steps in F02.
